A conventional photodiode array is described in, for example, the following Patent Document 1. A photodiode array such as an SiPM (Silicon Photo Multiplier) or a PPD (Pixelated Photon Detector) has a configuration in which APDs (avalanche photodiodes) are arrayed in a matrix state, and the plurality of APDs are connected in parallel, to read out a sum of APD outputs. When the APDs are operated in the Geiger mode, it is possible to detect feeble light (photons). That is, in the case where photons are made incident to an APD, carriers generated inside the APD are output to the outside via a quenching resistor and a wiring pattern for signal readout. Although an electric current flows in the pixels in which an avalanche effect occurs in the APD, a voltage drop occurs in the quenching resistor of approximately several hundreds of kΩ, which is directly connected to the pixels. Due to this voltage drop, a voltage applied to the amplified region of the APD lowers, and the multiplication action due to the avalanche effect is terminated. In this way, one pulse signal is output from an APD by incidence of one photon. Conventionally, a first contact electrode is provided in one of the semiconductor layers composing a p-n junction, and a resistive layer is connected to the wiring in the same plane of the wiring continued to the first contact electrode.
[Patent Document 1] European Patent Application Publication No. 1,755,171.